Subtract one layer from another

[ZanThrax]

I have a set of images that were all created with the same background elements. By combining sections of these, I've recreated the original background. Now I'd like to use that composite to remove the background from the original images. But I cannot figure out a way to do that. What I want is the ability to replace all the pixels in layer A with either white or with nothing if they match the pixel in layer B. Is there a layer blending mode that will do this that I'm not finding, or some combination of blending multiple layers that can achieve this?

[Ego Eram Reputo]

Try the XOR blend mode. It replaces matching pixels with black. Pixels that don't match will be colored.

[ZanThrax]

Is there any way to get pixels that don't match to either be 100% or 0% transparent?

 

XOR gives me very similar results to Negation - lots of black where the images are the same, and wild technocolor where they're different.

 

My end goal is to use the background that I've assembled to easily remove the background on a stack of images, replacing it with either white or transparency, and I'm trying to find a way to do that without having to try and select edges and manually erase pixels from each individual image.

[TechnoRobbo]

Work with a duplicate layer. XOR then merge. You can use the black as a selection (magic wand) . choose the original layer and delete

[ZanThrax]

That's getting me back to the problem I was originally having though - getting the wand to select the background and not bleed into the image that I'm trying to keep. If there was a binary output - either black to indicate a match or white to indicate a difference, that would work really well.

[TechnoRobbo]

Try this - Copy the match image in the clipboard, select the target image and run the plugin -only the different pixels remain. Background removed

 

TRsDifferenceMatte.zip